In-place merge of two sorted arrays (arr2 into arr1)

Coding: In-place merge two sorted arrays You are given two non-decreasing (ascending) integer arrays arr1 and arr2. Array arr1 has enough trailing space to hold all elements of arr2. Merge arr2 into arr1 in-place (O(1) extra space) so that arr1 remains sorted in ascending order. Input (stdin) Line 1: m n where arr1 has m valid elements and arr2 has length n Line 2: arr1 of length m+n (the last n entries are placeholders such as 0) Line 3: arr2 of length n Output (stdout) Print the merged arr1 (length m+n) as space-separated integers Constraints 0 <= m, n <= 2 * 10^5 Values in [-10^9, 10^9] Target time complexity: O(m+n) Example Input: 3 3 1 2 3 0 0 0 2 5 6 Output: 1 2 2 3 5 6 Follow-up (verbal) How would you merge if both arrays were sorted in descending order? If the arrays were unsorted, what would you do (you may modify the input arrays)? Example Input 3 3 1 2 3 0 0 0 2 5 6 Output 1 2 2 3 5 6